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Investigation of water-soluble high molecular preparation of symphytum grandiflorum DC (Boraginaceae)

Abstract:

According to data of IR, 1H NMR, gCOSY and 2D 1H/13 C gHSQCED experiments caffeic acid-derived polymer, namely poly[3-(3,4-dihydroxyphenyl)glyceric acid] (PDPGA) was detected in watersoluble high-molecular preparation of Symphytum grandiflorum DC (HMP-SG) by analogy with S. asperum, 13S. caucasicum, S.officinale and Anchusa italica high-molecular weight preparations. 2D 1H/C gHSQCED spectrum of HMP-SG exhibited that in contrast to polymers of other species of Symphytum, and likewise some polymer preparations from A. italica, most of the carboxylic groups of PDPGA from S. grandiflorum are methylated. Besides, the additional signals might have appeared in the gHSQCED spectrum of HMP-SG due to the presence of residual polysaccharide impurities. A 2D DOSY experiment of HMP-SG showed that both sets of signals of methylated in carboxylic group PDPGA and polysaccharides fell in the same horizontal. It means that they have the same diffusion coefficient. This would imply a similar molecular weight for the phenolic polyether and the polysaccharides. This would explain why, unfortunately, it proved not feasible to separate the phenolic polymer from residual polysaccharides by ultrafiltration. However, on the basis of data from IR, 1H NMR, gCOSY, gHSQCED and 2D DOSY experiments, the presence of methylated PDPGA in HMP-SG was sustained by analogy with high molecular preparations of A. italica.